The overall aim to clone genes and clarify genetic mechanisms that are postulated to play an important role in malignant transformation will be pursued by: 1. Attempting to clone one or more genes postulated to be responsible for maintaining normal cell functions and consequently designated tumorigenicity "suppressor" genes. These will be cloned with the aid of nontumorigenic hybrids of normal cells fused with carcinoma cells where the suppressors appear to be located on the chromosomes of the normal cell, primarily on the No. 11. Although their nature and function are not understood, they could be cloned by taking advantage of the decrease in expression that (antisense) RNA transcripts of a gene fragment that is inverted in respect to the normal direction of transcription exert on the endogenous complementary gene transcripts. This should allow suppressors to be isolated since inhibition of their expression in nontumorigenic hybrids would cause the hybrids to become tumorigenic, a change that can be recognized and selected for. Cloning such a gene would make it possible to ultimately determine its function, which could havve therapeutic implications. 2. Determining if loss of chromosome heterozygosity occurs in cervical carcinoma cells to clarify a potentially important mechanism of malignant transformation because loss of heterozygosity allows homozygous expression of tumorigenicity fostering changes even if they are recessive. For this purpose the chromosome complements of cervical carcinomas would be determined and correlated with the results of restriction fragment length polymorphic (RFLP) chromosome marker determinations of the same tumor cells and the subjects' constitutional cells. This will indicate if any losses found are due to simple loss of a homolog or to more significant changes such as loss of a homolog followed by one or more duplications of the remaining homolog or a segment of it. 3. Determining the potential of intraspecies hybrids made by fusing cells of two human tumors that originated in different tissues for studying other tumorigenicity associated genes. Some of these hybrids are tumorigenically suppressed, whereas others are much more tumorigenic than either of the parental cells. If specific chromosomes are found to cosegregate with these phenotypes these hybrids could ultimately be used for isolating genes that impart these phenotypes to the hybrids.